Prior to the present invention, a device has been taught in the prior art that is capable of recording a loss in pressure of a vehicle tire. See, for example, German publication De-PS 28 13 058. This prior art device is activated by the tire pressure, and signals the drop of a predetermined air pressure which is below a predetermined limit within the tire. This device has a range of measurement that is set by an upper and a lower pressure limit.
The problem with this device, however, is that it is unable to indicate a problem below a predetermined measurement range. In other words, this device is incapable of indicating a condition of a tire in which substantially all of the pressure has been lost, i. e., pressureless. This problem is especially serious in those cases where vehicle wheels with tire and rim emergency operating capabilities have a means by which they can operate for a relatively long distance, even with a completely flattened tire.
In those vehicles equipped with the above-described tire and rim systems, the rim surface is generally shaped in such a configuration that the flattened running surface of the tire, which is the tire surface in contact with the upper surface of the road, continues to act as the supporting surface for the tire. In the majority of the non-critical traffic situations to be encountered by an operator of the vehicle, such conditionally capable tire operation cannot be ascertained with any degree of certainty by the operator with the use of the prior aart devices presently known.